This invention relates to a flame retardant polyol composition and the method for preparing the composition.
U.S. Pat. No. 4,152,497 disclose that certain reaction products of chloral with urea, thiourea or sulfamide are useful as reactive flame retardants for polyurethane foam. The disclosed mono or dichloral urea compositions are solid products and therefore cannot be conveniently handled by foam manufacturers. In addition when the disclosed preparations are prepared in water the product then must be filtered, dried and redissolved in the polyol before use in the polyurethane foam. The acid catalyst used in the preparation also has to be removed by washing and this creats a disposal problem because a large volume of highly acidic wash water is generated. Another problem with this solid product is that substantially all of the water has to be removed prior to dissolving it in the polyurethane polyols since water interferes with the foaming reaction. This necessitates a lengthy drying period. When tetrahydrofuran is used as the solvent, it has to be removed by distillation in order to isolate the product; this also creates a disposal problem. In addition, tetrahydrofuran is flammable and dangerous to handle in plant equipment making this process undesirable commercially.
The present invention overcomes the disadvantages of the prior art solid compositions by being a liquid composition wherein the polyol is the solvent. The reaction products of the present invention are prepared directly in the polyol under anhydrous conditions. Hence, there is no need for filtering, washing or drying the product prior to using it in the manufacture of polyurethane foams. Another advantage of the present invention is that the reaction time is very short (i.e., on the average of less than five hours) as opposed to that of the prior art wherein up to three days were needed for completion of the reaction. Another important feature is that in the present invention no acid catalyst is required, thus eliminating a serious waste disposal problem.